<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style type="text/css">
        p {
            color: blue;
            text-align: center;
        }

        p strong {
            color: green;
            background-color: #d0f0f6;
            padding: 10px;
        }
    </style>
</head>
    <body>
        <p>Hello <strong>CSS！</strong></p>
    </body>
</html>